While walking with Hans de Kroon in the Ooijpolder, a largely agricultural area between Nijmegen and the German border, we pass hedgerows with hawthorn and alder buckthorn, grassy meadows, and freshly ploughed fields where thick slabs of clay soil gleam in the autumn sun. We pass many farmers on tractors who all greet Hans with a friendly wave.
Since the beginning of this year, the Ooijpolder has been a Living Lab for the professor of Ecology (see box), a research workplace where he and his colleagues hope to learn more about diverse and sustainable ecosystems over the next five years. He works closely with farmers and residents from the area. “By themselves, ecologists can’t make many changes. This is really something we have to do together with local inhabitants and scientists from other fields. Ecosystems are not limited to nature reserves, so you really have to organise the area as a whole.”
Earthworms
In 2017, De Kroon and colleagues sounded the alarm: their research showed that three-quarters of the insects had disappeared from nature reserves. The publication of this research created a widespread sense of urgency. “People were not aroused because insects are particular popular creatures, but because people realised that this was simply not right and that something really had to be done.”
He also sees this concern among farmers. “They are familiar with the problem of declining biodiversity and want to help reverse that trend,” he concluded from many conversations with farmers. “But they also set conditions, understandably; after all, they make a living with farming. If all you say is ‘nitrogen emissions have to be reduced’, the debate quickly becomes polarised. That is why we are specifically exploring new possibilities together in the Living Lab; we collaborate with the farmers to determine what works for both agriculture and for biodiversity.”
Collaboration starts with asking a lot of questions, not in an office, but while talking with farmers in their fields: What is your ambition for this landscape in five or ten years? What are you happy with and what would you like to change? How's your soil? Does it have earthworms? How often do you fertilise and plough? “Sometimes we say: ‘have you already thought of this?’ Or we start experimenting together: for example, what happens if you make pastures richer in herbaceous plants? Research has already shown that this makes the soil healthier and improves root formation, water retention and carbon and nitrogen sequestration. But farmers also want to know what it means for the nutritional value and yield of the pasture. It also raises questions that we, as scientists, do not immediately think of, such as: ‘Will I be bothered less by geese foraging on my pasture?’ These are all relevant questions that we try to tackle with research.”
Root power
More than ten years ago, the hedgerows were recreated in the Ooijpolder landscape. They provide a good habitat for insects, small mammals and breeding birds. At the same time, flower strips were planted that are also used as hiking trails. By not mowing them or only partially mowing them, farmers provide insects with safe overwintering locations.
De Kroon's research has shown that such herb-rich meadows also make the dikes safer. “We previously assumed that when space is limited, one species thrives at the expense of another, but the opposite appeared the case. In close vicinity, root growth is boosted, the species actually stimulate each other.” This ‘root power’ ensures a strong turf and a protective top layer on the dike. “At the same time, insects thrive in this vegetation and those flowering verges look fantastic. What a great combination.”
In this way, fundamental research has led to very practical applications. De Kroon is encouraged by the positive results, despite the alarming reports about climate change. “What gives me hope is that here in the Ooijpolder the insect community bounces back. That appears possible if you do the right things, such as restoring hedgerows and flower-rich dike grasslands. Research by one of my PhD students has shown that of the 360 species of wild bees in the Netherlands, nearly 100 – some of them very rare – are now present on these dikes. Our experiments here are extremely important to determine the measures that utilize the resilience of natural habitats and restore biodiversity. I also see it as our task to include people as participants in this process and to involve them in making a change. We have truly achieved something when residents start taking ownership of the process, when they take pride in their accomplishments, realized in their own environment.”
What can people do today to help nature?
“Don’t clean up the fallen leaves in your garden. They provide a habitat for hedgehogs and insects. Plant native flowering species. And take a look at Herenboeren.nl for information on environmentally friendly and fair food.
Living Labs
In addition to the Ooijpolder, the Netherlands has two more Living Labs for biodiversity recovery: a peat-soil pastureland region in the Alblasserwaard and the dune and flower bulb region of South Holland. With funding of €1 million per lab from the Dutch Research Council (NWO), scientists from Radboud University, the Naturalis Biodiversity Centre and the Netherlands Institute of Ecology will spend the next five years performing research at these locations on how to restore biodiversity in various types of landscapes. The Nijmegen professor of Ecology Hans de Kroon is the consortium leader for this project, which should result in effective approaches for improving biodiversity and sustainability. The Living Labs work together with the national 'Delta Plan for Biodiversity Recovery'.
Text: Bea Ros. Photo: Flip Franssen